The research projects in this Asthma and Allergic Disease Center deal with the study of basic mechanisms relevant to the expression of the atopic response. The first project has as its overall objective to evaluate thymus dependent immune function in patients with demonstrated tendencies toward excessive IgE antibody production to determine whether a relative broad or specific T cell deficiency exists in such individuals. This information could be of critical importance in guiding future therapy, since it may point to a need to manipulate the immune response to augment allergen-directed T cell responses in such patients. The objective of the second project is to evaluate immunologic effector systems in patients with excessive IgE antibody production and undue susceptibility to infection. These include patients with atopic dermatitis and patients with four known types of immunodeficiency diseases in which serum IgE concentrations are elevated.